package com.awx.client.widget.form;

import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.io.Serializable;

/**
 * A vertical layout manager similar to java.awt.FlowLayout. Like FlowLayout
 * components do not expand to fill available space except when the horizontal
 * alignment is <code>BOTH</code> in which case components are stretched
 * horizontally. Unlike FlowLayout, components will not wrap to form another
 * column if there isn't enough space vertically. VerticalLayout can optionally
 * anchor components to the top or bottom of the display area or center them
 * between the top and bottom. Revision date 04 April 1999
 *
 * @author    Colin Mummery e-mail:equitysoft@iname.com
 *      Homepage:www.kagi.com/equitysoft - Based on 'FlexLayout' in Java class
 *      libraries Vol 2 Chan/Lee Addison-Wesley 1998
 * @version   $Revision: 1.4 $
 */
public class VerticalLayout implements LayoutManager, Serializable
{
    /**
     * The horizontal alignment constant that designates centering. Also used
     * to designate center anchoring.
     */
    public final static int CENTER = 0;

    /**
     * The horizontal alignment constant that designates right justification.
     */
    public final static int RIGHT = 1;

    /**
     * The horizontal alignment constant that designates left justification.
     */
    public final static int LEFT = 2;

    /**
     * The horizontal alignment constant that designates stretching the
     * component horizontally.
     */
    public final static int BOTH = 3;

    /**
     * The anchoring constant that designates anchoring to the top of the
     * display area.
     */
    public final static int TOP = 1;

    /**
     * The anchoring constant that designates anchoring to the bottom of the
     * display area.
     */
    public final static int BOTTOM = 2;

    /** The vertical vgap between components...defaults to 5. */
    private int vgap;

    /** LEFT, RIGHT, CENTER or BOTH...how the components are justified. */
    private int alignment;

    /**
     * TOP, BOTTOM or CENTER ...where are the components positioned in an
     * overlarge space.
     */
    private int anchor;

    //Constructors
    /**
     * Constructs an instance of VerticalLayout with a vertical vgap of 5
     * pixels, horizontal centering and anchored to the top of the display area.
     */
    public VerticalLayout()
    {
        this(5, CENTER, TOP);
    }

    /**
     * Constructs a VerticalLayout instance with horizontal centering, anchored
     * to the top with the specified vgap.
     *
     *@param vgap  an int value indicating the vertical seperation of the
     *             components
     */
    public VerticalLayout(int vgap)
    {
        this(vgap, CENTER, TOP);
    }

    /**
     * Constructs a VerticalLayout instance anchored to the top with the
     * specified vgap and horizontal alignment.
     *
     * @param vgap       an int value indicating the vertical seperation of the
     *                   components
     * @param alignment  an int value which is one of <code>RIGHT, LEFT,
     *                   CENTER, BOTH</code> for the horizontal alignment.
     */
    public VerticalLayout(int vgap, int alignment)
    {
        this(vgap, alignment, TOP);
    }

    /**
     * Constructs a VerticalLayout instance with the specified vgap, horizontal
     * alignment and anchoring
     *
     *@param vgap       an int value indicating the vertical seperation of the
     *                  components
     *@param alignment  an int value which is one of <code>RIGHT, LEFT, CENTER,
     *                  BOTH</code> for the horizontal alignment.
     *@param anchor     an int value which is one of <code>TOP, BOTTOM,
     *                  CENTER</code> indicating where the components are to
     *                  appear if the display area exceeds the minimum
     *                  necessary.
     */
    public VerticalLayout(int vgap, int alignment, int anchor)
    {
        this.vgap = vgap;
        this.alignment = alignment;
        this.anchor = anchor;
    }

    /**
     * Lays out the container.
     */
    public void layoutContainer(Container parent)
    {
        Insets insets = parent.getInsets();
        //NOTUSED Dimension dim = layoutSize(parent, false);
        synchronized (parent.getTreeLock())
        {
            int n = parent.getComponentCount();
            Dimension pd = parent.getSize();
            int y = 0;
            //work out the total size
            for (int i = 0; i < n; i++)
            {
                Component c = parent.getComponent(i);
                Dimension d = c.getPreferredSize();
                y += d.height + vgap;
            }
            y -= vgap; //otherwise there's a vgap too many
            //Work out the anchor paint
            if (anchor == TOP)
            {
                y = insets.top;
            }
            else if (anchor == CENTER)
            {
                y = (pd.height - y) / 2;
            }
            else
            {
                y = pd.height - y - insets.bottom;
            }
            //do layout
            for (int i = 0; i < n; i++)
            {
                Component c = parent.getComponent(i);
                Dimension d = c.getPreferredSize();
                int x = insets.left;
                int wid = d.width;
                if (alignment == CENTER)
                {
                    x = (pd.width - d.width) / 2;
                }
                else if (alignment == RIGHT)
                {
                    x = pd.width - d.width - insets.right;
                }
                else if (alignment == BOTH)
                {
                    wid = pd.width - insets.left - insets.right;
                }
                c.setBounds(x, y, wid, d.height);
                y += d.height + vgap;
            }
        }
    }

    public Dimension minimumLayoutSize(Container parent)
    {
        return layoutSize(parent, true);
    }

    public Dimension preferredLayoutSize(Container parent)
    {
        return layoutSize(parent, false);
    }

    /**
     * Not used by this class.
     */
    public void addLayoutComponent(String name, Component comp)
    {
    }

    /**
     * Not used by this class.
     */
    public void removeLayoutComponent(Component comp)
    {
    }

    public String toString()
    {
        return getClass().getName()
            + "[vgap="
            + vgap
            + " align="
            + alignment
            + " anchor="
            + anchor
            + "]";
    }

    private Dimension layoutSize(Container parent, boolean minimum)
    {
        Dimension dim = new Dimension(0, 0);
        Dimension d;
        synchronized (parent.getTreeLock())
        {
            int n = parent.getComponentCount();
            for (int i = 0; i < n; i++)
            {
                Component c = parent.getComponent(i);
                if (c.isVisible())
                {
                    d = minimum ? c.getMinimumSize() : c.getPreferredSize();
                    dim.width = Math.max(dim.width, d.width);
                    dim.height += d.height;
                    if (i > 0)
                    {
                        dim.height += vgap;
                    }
                }
            }
        }
        Insets insets = parent.getInsets();
        dim.width += insets.left + insets.right;
        dim.height += insets.top + insets.bottom + vgap + vgap;
        return dim;
    }
}
